Knee lock for artificial limbs



July 10, 1951 J. E. HANGERJJI KNEE LOCK FOR ARTIFICIAL LIMBS 4Sheets-Sheet 1 Filed May 19, 1948 o INVENTOR. JamiesElHangezgH 7 qwmufJuly 10, 1951 J. E. HANGER,I]I

KNEE LOCK FOR ARTIFICIAL LIMBS 4 Shets-Sheet 2 Filed May 19, 1948 I E!Z.

INVENTOR. EHan 381, H

Jalnes BY July 10, 1951 -J. E. HANGERJE KNEE LOOK FOR ARTIFICIAL LIMBS 4Sheets-Sheet 5 Filed May 19, 1948 INVENTOR.

Jamesl'l'flanyenm BY y 10, 1951 J. E. HANGER, 111: 2,560,286

KNEE LOCK FOR ARTIFICIAL LIMBS F iled May 19. 1948 4 Sheets-Sheet 4 IN VEN TOR.

Patented July l0, 195i UNITED S TAT ES PATENT O F Fl "2,560,286

KNEE LOOK FOR ARTIFICIAL LIMBS James E. Hanger, ,II-I, Washington, .D.13., assignor to Metal Limb Manufacturerall-nc Washington, D. (3., acorporation of Delaware Application .May 19, 1948, Serial No. 27,87 6

15 Claims.

The present invention relates to a new and improved knee lock forartificial limbs.

An important feature of the invention consists in associating with theknee joint of an artificial limb, a releasable locking mechanismincluding means for maintaining the thigh member and the calf member ofan artificial limb in a vertical or straight position when the wearer istaking a forward step, and providing means operable by the applicationof pressure on the ball or too of the foot to release the lockingmechanism. In order to re-engage the locking connection of :the thighmember with the calf member, when the thigh member and calf member arein vertical or aligned position, it is necessary for the wearer to applyweight on the heel of the foot which causes the locking mechanism to bemoved to its latched position, andthus prevent bending :of the thighmember and the calf member at the knee joint or buckling of the knee asthe wearer ;pro ceeds to take a forward step. As the body of the wearerapproaches a vertical position above the artificial leg, hisweightshifts over the 'knee center andit is no longer necessary for theartificial leg to require the knee lock to prevent it from buckling atthe knee joint. Therefore, as the body of the wearer moves forward,.depression of the toe or ball of the foot causesthe knee lock tounlatch allowingthe wearerto bend the knee so as to begin the nextforward step,

thus providing simple,eificient and positive means for fiexingthe kneejoint, and for preventing the collapse-of the limb when the weight ofthe-wearer is placed on the knee joint in the act of walking.

A further object consists in associating with the knee lock mechanism, alost motion connection which is operable when the locking 'pawl'is movedout of engagement with a latch on vthe thigh member and the foot memberis returned to its normal position, to prevent engagement-of the pawlwith the latch upon the return ;-movement of the foot member.Additionally, yieldable means-are provided when the pawl is moved intolocking engagement with the latch forallowingreturnof the foot member toits normal horizontal position without disturbing the locking.connection'of the pawl with thelatch member-so that the thigh member.and the calf member will be maintained in vertical alignment until thetoe .of-the .foot is again depressed.

Another object consists in providing a knee lock mechanism which .isconnected to .the .calf member and includes a pawl arranged to be moved,intoand out of engagement with .pawl

2 receiving means on the thigh member. h'control bracket is fixed to thelock mechanism and has means rotatably connected thereto whichareoperatively connected to the pawl, and also to an operating rod whichis connected to the ,foot member, so that upon rocking' of the footmember relative to the calf member fromits normal position and in onedirection when the thigh member and calf member are in aligmnent, foractuating the rotatable means to move .the pawl into locking engagementwith the latch means,

andupon :rocking the foot1-memberfrQm -its ;nor- 7 mal position and inan opposite direction, :for actuating the rotatable means to ,mov e-.the ;paw1 out ofengagement with the latch ,mea-ns.

O.t-her objects and advantages of the invention vwill become apparentfrom the following description-when taken in conjunction with theaccompanying claims and-drawings. t

Referring to the drawings in which are disiclosed several preferredembodiments of ,the in- .;vention:

Figure l is a vertical sectional view of anartificial limb constructedin accordancewith-the present invention, showing the --th-igh portionlocked to the -calf portion and the parts in-the .EDQsi-tion they assumewhen the wearer -takes a :forward step.

.Figurezis anenlarged detailedrearview of the knee jointshown inFigure,1.

. Figure .3 a sectional view taken substantially alongthe dine.3.,3.zof, Figure l Figure 4 is an enlarged verticaksectional viewtakenlsubstantially alongthe line.44.of;Eigure;2.

Figure :5 :is an enlarged detailed :sectionalwievv staken substantiallyalong the line 5-5 .of Figure 4.

.Figure 6 :is anxenlarged detailedsectional xview 'takensubstantiallyalong the linens-6 .Of'ZEIig ure 14.

Figure .7 is a sectional view. taken substantially along-the line 1-? ofFigure '6.

Figure 8 is -a detailed side view showing'the position -of the frictionlever, transfer pin, and operating rod when'the parts are-in lockingposition.

-Figure 9 is 'a view similar to Figure f3 showing the parts when thelocking. mechanismis moved to its released position.

Figure 10 is an enlarged "sectional plan wi'ew taken substantially alongthe '1ine. |"ll ll]. of I'Fig- 111191. m ,Figure l1 is a sectionalviewtaken-subfillg ptially along the line fill-1H ,o'f .Eigure .110.

Figure 12 is a perspective view of the transfer lever.

Figure 13 is a perspective view of the friction lever.

Figure 14. is a perspective view of the control bracket.

Figure 15 shows the position of the artificial limb as the leg is movedforward, and shows the locking pawl in full lines just prior to theoperating rod taking up the lost motion and moving the locking pawl intoengagement with the bot tom of the thigh member.

Figure 16 shows the position of the artificial limb and the lockingmechanism when the body of the wearer is moved over the artificial limbwith the parts in locked engagement, and also shows in dotted lines therelease of the locking mechanism after the application of pressure onthe ball of the foot and when the knee is bent to begin the next forwardstep.

Figure 17 is a vertical rear section-of a modified form of artificialleg constructed in accordance with the present invention.

Figure 17a is an enlarged vertical sectional view taken substantiallyalong the line lla-l'|a of Figure 19;

Figure 18 is a rear view of the knee joint structure shown in Figure 17.

' Figure 19 is a sectional View taken substantiall y at right angles tothat shown in Figure 17, and

Figure 20 is an enlarged sectional view taken substantially along theline 2ll20 of Figure 19.

' Referring to the drawings, the artificial limb constructed inaccordance with the present invention includes a hollow thigh member orsection 21, a hollow calf member 22, and a foot member' 23,'which maybemade of any suitable light, durable composition or metal. The bottom ofthe thigh member is curved as at 24 and shaped to fit; within the upperhollow portion of the calf member '22 in order to provide a movable kneejoint and permit free movement of the knee joint without danger of agarment of the wearer becoming caught between the joint. Extendingupwardly from opposite sides of the calf portion 22 adjacent the topthereof, are a pair of fixed bearing lugs 25 (Fig. 2) having transversealigned openings through which extends a fixed knee bolt 21 providedwith enlarged head portions 28 at its opposite ends that bearagainst thelugs 25. The thigh member 2| adjacent the knee joint 24 is rotatablymounted on the knee bolt 27 and the bottorn or the knee joint 24 isprovided with a notch or recess 29. A metal guard plate lB having anopening [Si-registering with the recess 23, may be secured by the screws20 to the bottom of the knee joint 24, (Fig. 3).

- The locking mechanism associated with the artificial limb, may includea metal member or bar 33 having at its upper end a lateralprojecting'portion 3| (Fig. 4) provided with a transverse opening 32through which loosely extends the knee bolt 21. The bar is preferablyformed with a depending channel-shaped portion or member 33 whichextends downwardly through a central slot 34 in the rear of the thighmember 2 l', and has spaced parallel sides 35 (Fig. 3). The dependingportion 33 is firmly secured to the rear wall of the calf section in anysuitable manner such as by the retaining screws 36. A flat spacer Spring31 may be connected at its lower end as at 38 (Fig. 4) to the portion 33and has its upper portion extending over and engaging the underside of atransverse pin 39 as at 40. A locking pawl or lever 4| is pivoted at oneend as at 42 to the aseofas 4 spaced sides 35 of the channel portion 33of the member 33, and is provided at its opposite end with a nose 43which is arranged to be moved into the recess or detent 23 when thethigh member 2| and the calf member 22 are in alignment, so as to lockthese members together and prevent buckling of the artificial limb atthe knee joint. The end of the pawl 4| may be faced with a leathercovering or the like 4| to prevent scraping of the pawl on the knee inte event the lock does not entirely disengage. The forward wall of theslot 34 may be provided with a rubber buffer 44 that bears against thebar 33 when the latter is in its vertical position. A control bracket ormember 45 is provided at one end with a bent flange portion 46 (Fig. 14)which extends into the channel member 33 (Fig. 3) and may be securedthereto by the retaining bolt 33 and the spaced screws 4?. The oppositeend of the control bracket 45 terminates in an enlarged circular head 48having a central opening 49. A friction lever 50 is provided at one endwith an enlarged circular portion 5! having an opening 52 (Fig. 13)which registers with the opening 49 in the control bracket 45. The lever50 has intermediate its ends, an enlarged opening 53 and ter- Inmates atone end thereof in a laterally extending flange 33 formed with avertical through opening 55 through which loosely extends a slidableconnecting rod 56 having a head 5'! at its lower end and positionedbelow the flange 54. The upper end of the rod 56 extends into an opening58 in a boss or member 59 so as to be rigidly secured thereto such as bywelding or the like. The upper end of the boss 59 is bifurcated so as toform the spaced arms 69 which overlap the pawl 4! and are pivotallyconnected thereto by the pin 6i (Fig. 5). Surrounding the rod 56 andconfined between the flange 54 and the boss 59 is a coil expansionspring 62 which provides a lost motion connection between the frictionlever 50 and the pawl 4| in a manner and for the purpose that willsubsequently be described. A transfer lever or member 63 is positionedadjacent the control bracket 45 opposite to the friction lever, and hasat one end an opening 64 which registers with the opening 49 in thecontrol bracket, and has extending laterally and outwardly therefrom atransfer pin or stud 65 which extends into the opening 53 in thefriction lever and is of much smaller diameter than the opening 53 so asto be loosely mounted therein for the purpose of permitting lost motionor movement of the transfer lever a limited or predetermined distancebefore operating the friction lever. The pin 65 may carry, a flexiblerubber sleeve 65' also of smaller diameter than the opening 53 andarranged to engage the wall thereof upon vertical movement of the rod18. The transfer lever 63 is also formed with an opening 66 throughwhich rotatably extends a screw 61 that is threaded as at 68 to a sleeve63 to permit independent movement of the transfer lever relative to thesleeve 69. A spring metal washer H3 is positioned adjacent the frictionlever 50 and has a central opening which registers with the opening 52on the control lever and may be spaced therefrom by a friction fiberwasher H. A shoulder washer 12 having a threaded central bore 13 (Fig.5) registers with the openings in the control bracket 45, friction lever50, transfer lever 63, and spring washer Hiv so as to receive a threadedbolt 14 in order to firmly clamp these parts in position. The shoulderwasher 12 preferably carries a metal washer 15 which bears against thetransfer lever escapee 6'3. Interposed between the transfer lever andthe bracket 45 may be a friction fiber washer I6. A threaded locking nutI1 is connected to the threaded bolt I4 so as to bear against theshoulder washer I2 in order to releasably maintain these parts in afixed position. An operating rod I8 has its upper end portion i9extending through the sleeve 59 and a tubular bearing member 80 (Fig. 6)which is internally threaded as at ill to receive the external threadson a reduced split portion 82 of the sleeve 69. The upper end of theportion 82 may be provided with flared arms 83 through which extends theouter end of the portion I9 of the rod I8. It will be seen that screw 61extending into the sleeve 69 bears against the portion I9 of the rod soas to provide means for maintaining the rod 78 in any desired adjustedposition.

The foot member 23 is preferably formed with a hinged toe section 84that is connected to the foot section by a rubber insert 95. The footmember also has an intermediate raised ankle portion 86 and recesses 81and 99 on opposite sides of the raised portion 95. The lower end orbottom 94 of the calf member 22 is provided with a depending curved lipportion or member 89 (Fig. 1) which bears against a rubber insert 90 infront of and adjacent to the raised portion 85. Within the heel recess88 is a resilient rubber plug 9I which at its lower end bears against arubber strip 92 and is of sufficient length as to extend upwardly into arecess es formed in the bottom wall 94 of the calf member 22. The rubberinserts 90 and SI on opposite sides of the pin 95 provide yieldablemeans for normally maintaining the foot member 23 in substantially ahorizontal position, when downward pressure is removed from the toe andheel sections of the foot. A fixed transverse ankle pin 95 is embeddedin the bottom 94 of the calf member 22, and the foot member 23 isrotatably connected to the calf member 22 by a looped or invertedU-shaped bolt 96 that extends over the pin 95 and has depending threadedarms 9! projecting through openings 98 in the raised portion 85. Thelower ends of the arms 91 extend into a recess 99 so as to be connectedto the clamping bolts I09. A friction plate IOI within the recess 99 maybe positioned so as to be engaged by the bolts I00 when the U-bolt 96 issecured in position. The U-bolt 96 has extending outwardly therefrom anarm I02 (Fig. 10) which is pivotally connected to a clevis I03 by thepin I00 (Fig. 11). The lower end of the rod I8 extends into an openingI05 in the top of the clevis I03 so as to be secured thereto.

The foot member 23 is movably connected to the lower end of the calfmember 22 by the U-shaped bolt 95 through its pivotal connection withthe pin 95, so that the foot may be rocked about its pivot in such amanner that the rubber insert 90 will allow a certain forwarddisplacement of the foot member while the rubber plug 9|, which is moreresilient than the plug insert 90, will allow a greater rearwarddisplacement of the foot member. A yieldable strip of rubber or the likeI06 may be positioned below the rubber insert 85 at the ball of the footand overlaps both the foot member 23 and the toe section 84. The bottomof the foot from the instep over and above the toe 9 may be covered witha strip of leather or the like I01, and a flexible strap or piece I09may be positioned in the space between 6 rubberportion 92 of the heelmay similarly be covered with a leather piece I09 that is suitablysecured to the rear portion of the foot member 23. In operation of theartificial limb, assuming that the thigh member 2| and the calf member22 are in vertical alignment and the latch mecham's'm is released andabout to be moved to its locked position to prevent collapse of the kneejoint and the user moves his artificial leg forward to take a step (Fig.15), the knee of the wearer will 'be in a straight position and as theweight of the body is placed against the heel 92, the rubber plug 9| isdepressed within the recess 88 causing the U-shaped bolt 95 to rock onthe pin 95 and the arm I02 to be moved upwardly, thus raising the rodI8, which in turn causes the transfer lever 63 and the friction lever 59together with the metal and fiber washers, and the pin I0 to be rotatedrelative to the fixed control bracket 45. A the friction lever isoperatively connected by the rod 56 to the pawl l I, this upwardmovement raises the pawl so that the nose 43 is moved and maintainedwithin the opening or catch 29 in the bottom of the knee portion 94(Fig. 4-). In other words, the pawl AI is moved from its disengagedposition as shown in full lines to its locked position as shown indotted lines in Figure 15. The transfer pin 65'i also moved upwardly inits slot 53 (Fig. 8) so as to bear against the upper wall thereof inorder to cause simultaneous movement of the friction lever 59 and thetransfer lever 93 when "the rod I8 is raised beyond a predeterminedlimit. It will be seen that during this forward movement of theartificial leg, that the locking mechanism maintains the thigh member 2|in a straight fixed position relative to the calf member 22 so as toprevent buckling of the artificial limb and that it is impossible tobend the leg-or for the members to buckle at the knee as the wearertakes a forward step and walks on the top of the shoe member 23 and thetoe '84 so as to underlie the leather covering I01. The

his artificial leg. As the wearer approaches a vertical position abovethe artificial leg (Fig. 16), his weight shifts over the knee center andit is no longer necessary for the leg to have a knee lock to prevent itfrom buckling. It mi ht be mentioned that the instep rubber functions tostop the ankle movement of the foot member 23 as the wearers body movesforward so that when he depresses the toe portion 89, the artificiallimb assumes the position as shown in dotted lines in Figure 16, withthe result that as the pressure is applied to the ball of the foot, theyieldable rubber inserts 85 and 9e are compressed and the foot member 23moved to an inclined position so as to cause the. U-shaped bolt 96 torock on the pin and move the arm I02 downwardly. This movement of therod I02 lowers the operating rod l8 thus causing the locking mechanismto move the pawl lI out of engagement with the recess 93 so that theknee joint may be flexed. As the compressed rubber inserts 35 and 99return to their normal positions, the pawl 4! is prevented from beingmoved into locking engagement with the recess 93 by the lost "motionconnection between the transfer'pin 65 in the opening 53 of the frictionlever 50 which allow a predetermined upward movement of the rod I9without disturbing the disengaged position of the pawl 4|. In order toreengage the pawl it is, of course, necessary to put the weight on theheel 92 of the foot (Fig. 15) which causes the heel rubber 9I to bedepressed. Durin this upward movement of the rod I8 the lost motionbetween the'transfer pin 55 and the friction lever 50 is' taken up bypin 35 engaging the upper wall of the opening 53 (Fig. 8). When the heelrubber 9| and the foot member 23 return to their normal position (Fig.16), it will not cause disengagement of the pawl 44, which remainslocked until the toe 84 of the foot is again depressed. This is due tothe fact that when the pawl AI is moved to its locked position and thefoot member returns to its normal horizontal position, displacement ofthe pawl is prevented by the compression of the spring 62, whichfunctions to take up the excess amount ofmovement of the friction lever50 by the engagement of the lug 54 with the lower end of the spring 62so as to compress the latter as the lug 54 i moved upwardly and awayfrom the head 51 of the connectin rod 56 (Fig. 8), without disturbing orcausing any vertical movement to be imparted to the connecting rod 56and the pawl 4!, so that the pawl will remain locked until the toe ofthe foot is again displaced. In other words, the spring 62 constitutes alost motion means which functions to take up the excess amount ofmovement of the friction lever 5| caused by the considerabledisplacement of the rubber heel member 9| when the latter is compressed.The adjustment of the shoulder friction washer E2 on the bolt I4 is justtight enough to overcome the pressure of the spring 62 on the connectingrod 55 so that the latter remains set against the pressure of spring 62until it is moved by the transfer pin. Thus, it will be seen that thelocking mechanism allows the knee to remain free to swin when it isunlatched and until the weight of the wearer is applied to the heel ofthe foot. Consequently, the wearer may convenientlyv bend the artificiallimb at the knee to sit down or get up without causing the parts to bemoved into locking engagement, and the knee will remain unlocked untilthe foot is straightened out and pressure applied to the heel (Fig.

In the modified form of the invention shown in Figures 17 to 21inclusive, the thigh member III] is pivotally connected as at I I l tothe calf section H2 by a transverse pin H3. The bottom H4 of the thighsection i is which forms the knee joint is provided with a centrallydisposed curved slot IE5 that extends above the transverse pin H3.Within the slot H5 is a horizontal bar H3 which terminates at one end ina tubular portion or bearing sleeve H'I (Fig. 19) which preferably islocked to the transverse pin H3 by a set screw I I8. Extendingdownwardly and from the opposite end of the bar H6 so as to be movableas a. unit therewith, is a depending arm I I9, which is clamped orotherwise secured at its lower end as at I28 to a transverse bracket orstrap I21 that is connected to the inner forward wall of the calf memberH2 by the bolts I22. The lower intermediate portion of a flexible strapI23 passes under a roller I2l carried by the bar HE and is suitablyconnected at its upper ends to the waist belt of the artificial leg.

The bottom or knee joint portion H4 of the thigh member I I8 adjacentone of the side walls of the slot H5 such as the side I25, is providedwith a recess or looking catch I26 that may be protected by a metal.plate I2!- having an opening registering with the recess I25. A lockingmechanism substantially similar to the knee lock previously described,is connected to the rear inner wall of the calf, member H2 andpreferably in cludes a vertical bar or member I28 having lateralprojecting side arms I29 which are curved to conform with the curvatureof the inner rear wall of the calf member H2 so as tobe secured theretoby the bolts Hill. The bar I28 above the arms I29 may be formed withspaced lugs I3I to which is pivotally connected as at I32 a locking pawlor latch E33. lhe bar I28 is positioned centrally and substantially inalignment with the slot H5 and in order that the pawl I33 may be movedinto and out of locking engagement with the recess I25 in the side wallI25 of the bottom H4, the latch I33 is bent or ofiset as at I34 (Fig.20) and has a forwardly extending free portion I35 provided with an armI36 that engages the recess I26 when the thigh member IIB is moved intoalignment with the calf member I I2 and the pawl I33 is raised to itslocked position. A control bracket I3? is connected as at 538 to the barI28 and has associated with it a friction lever I39, a transfer leverI49, a spring washer IGI, a metal washer hi2, and fiber washers U32which are clamped together by a threaded bolt I43 and nut I42 so as tobe rotatable upon the actuation of the operating rod 54%. The rod M4 ispivotally connected as at I i-5 to the transfer lever MB. The coilspring Hi5 carried by the connecting rod I4! provides a lost motionconnection when the pawl I33 is in locked. engagement with the recessI26 and allows the foot member to be returned to its normal positionafter the heel has been moved to lock the pawl, without disturbing thepawl. The friction lever iBQ has an enlarged opening I39 for receiving atransfer pin M9 on the lever I49 for providing a lost motion connectionsimilar in operation to the pin {55 (Fig. 3) The lower end of theoperating rod Hi l is connected to an inverted U-shaped bolt carried bythe foot member and similar in construction and operation to the foot 23and its associated parts previously described. It will be noted that inthis form of the invention the knee lock is not connected to the pin H3,and pawl H33 is offset so as to be moved into and out of lockingengagement with its complementary oilset recess IZE, as contrasted tothe centrally disposed latchd l and its associated parts previouslydescribed. Otherwise the construction and operation of both forms oflocking mechanisms are the same. In both forms of the invention in orderto release the locking mechanism, it is necessary to put the weight onthe ball of the foot. To move the latch into locking engagement with itsrecess when the knee is in a straight position, it is required to putthe weight of the user on the heel of the foot.

It will be seen that by reason of the novel locking mechanism as shownin the several figures of the drawing, that simple, eiiicie t,economical and positive means are provided for preventing blockling ofthe knee joint when the artificial limb is moved forward when taking astep, and that the knee lock can only be released upon the applicationof pressure to the ball of the foot. Moreover, this locking mechanismallows the knee to remain free to swing when it is unlatched until thethigh member and calf member are moved in alignment and Weight isapplied to the heel of the foot. The knee lock is compact andconstitutes a unitary structure which may be included as a permanentpart of an artificial limb or may be readily installed on a usedartificial limb at a minimum expenditure of time and effort.Additionally, the parts of the locking mechanism are convenientlypositioned so as to be accessible for the purpose. of inspection andrepair.

The invention is capable of various modificathigh member provided with acatch, a calf member pivotally connected to said thigh member,

a foot member pivotally connected to said calf member, a knee lockmechanism connected to the calf member and including a pawl. arranged tobe moved into and out of engagement with said catch, a control bracketconnected to the" calf member, rotatable means connected to said controlbracket, means operatively connecting said rotatable means to said pawl,an operating rod connected at its lower end to said foot member, meanspivotally connecting the upper end of said rod to said rotatable means,a lostmotion connection between the movable means and the pawl forallowing vertical displacement of the operating rod a predetermineddistance when they pawl is disengaged from the catch without disturbingthe position of the pawl, and-yieldable meansbetween the movable meansand the pawl for allowing vertical movement of the operating rod withoutdisturbing the pawl when the latter is in looking engagement with thecatch, the parts being constructed and arranged so that upon rockingmovement of the foot member in one direction to cause the operating rodand the rotatable means to move the pawl into engagement with the catchand upon movement of the foot member in an opposite direction to actuatethe operating rod and the rotatable means to disengage the pawl from thecatch.

2. An artificial limb having in combination, a.

f thigh member provided with a catch at the lower end thereof, a calfmember pivotally connected to said thigh member, a foot member pivotallyconnected to said calf member, knee lock mechanism connected to the calfmember and includof engagement with said catch, a control bracketconnected to the calf member, a friction lever on one. side of saidcontrol bracket, means operatively connecting the friction lever to saidpawl, a transfer lever on the opposite side of said bracket, meansrotatably comiecting said levers to said control bracket, an operatingrod connected at its lower end to said foot member, and means pivotallyconnecting the upper end of the operating rod to said transfer lever,the partsbeing constructed and arranged so that upon rocking of the footmember in one direction for rotating the friction lever and the transferlever to move the pawl into engagement with said catch when the thighmember is in alignment engagement with said catch, a control bracketconnected to the calf member, a friction lever on one side of saidcontrol bracket, means operaing a pawl arranged to be moved into and outmeans pivotally connecting th upper end of the operating rod to saidtransfer lever,- andmeans providing a lost motion connection betweensaid transfer lever and said friction lever, the parts being constructedand arranged so that upon rocking of the foot member in one directionfor rotating the friction lever and the transfer lever to move the pawlinto engagement with said catch when the thigh member is in alignmentwith the calf member, and when thefoot member is rocked in an oppositedirectionfor rotating the friction lever and the transfer lever forreleasing engagement of the pawl with said catch.

4. An artificial limb having in combination, a thigh member providedwith a catch at the lower end thereof, a calf member pivotally connectedto said thigh member, a foot member pivotally connected to said calfmember, knee lock mechanism connected to the calf member and including apawl arranged to be moved into and out of engagement with said catch, acontrol bracket connected to the calf member, a friction lever on oneside of said control bracket, means operatively connecting the frictionlever to said pawl, a transfer lever on the opposite side of saidbracket, means rotatably connecting said levers to said control bracket,an operating rod connected at its lower end to said foot member, meanspivotally connecting the upper end of the operating rod to said transferlever, and yieldable means for providing a lost motion connectionbetween the frictionlever and said pawl. for allowing vertical movementof the operating'rod without disturbing the pawl whenv the latter is inlocked engagement with the catch, the parts to said thigh member, a footmember pivotally connected to said calf member, knee lock mechanismconnected to the calf member and including a pawl arranged to be movedinto and out of engagement with said catch, a control bracket connectedto the calf member, a friction lever on one side of said controlbracket, means operatively connecting the frictionlever to said pawl,yieldable means providin a lost motion connection between the. frictionlever and the pawl for allowing displacement of the friction leverwithout disturbing the position of the pawl, a transfer lever on theopposite side of said bracket, means. rotatably connecting said leversto said control bracket, an operating rod connected at its lower end tosaid footmember, means pivotally connecting the upper endof the.operatingrod to said transfer lever, and means providing a lost motionconnection between said transfer lever and said friction lever, theparts tively connecting the friction lever to said pawl,

a transfer lever on the opposite side of said bracket, meansrotatablyconnecting said levers to said control bracket, an operating rodconnected at its lower end to said foot member,

' rotating the'friction lever and the transfer lever 11' for releasingengagement of the pawl with said catch.

6. In an artificial limb, a thigh member having a locking catch in thebottom thereof, a calf member, pivot means extending transversely of thethigh member for connectin the upper end of the calf member thereto toprovide a movable knee joint, a bar rotatably connected to said pivotmeans and extending downwardly into said calf member, means connectingsaid bar to said calf member, a foot member pivotally connected to thelower end of said calf member, a locking pawl pivotally connected tosaid bar and arranged to be moved into and out of locking engagementwith said catch, a control bracket connected to said bar, an operatingrod operatively connected at its lower end to said foot member, afriction lever operatively connected to said pawl, a transfer leverpivotally connected to said operating rod, means rotatably connectingsaid friction lever and said transfer lever to said control bracket, andmeans providing a lost motion connection between said transfer lever andsaid friction lever, the parts being constructed and arranged so thatupon rocking of the foot member relative to the calf member in onedirection, when the thigh member and calf member are in alignment, formoving the pawl into locking engagement with said catch and when saidfoot member is moved in an opposite direction relative to the calfmember for releasing the engagement of the pawl with said catch.

'7. In an artificial limb, a thigh member having a locking catch in thebottom thereof, a calf member, pivot means extending transversely of thethigh member for connecting the upper end of the calf member thereto toprovide a movable knee joint, a bar rotatably connected to said pivotmeans and extending downwardly into said calf member, means connectingsaid bar to said calf member, a foot member pivotally connected to thelower end of said calf member, a looking pawl pivotally connected tosaid bar and arranged to be moved into and out of locking engagementwith said catch, a control bracket comiected to said bar, an operatingrodoperatively connected at its lower end to said foot member, afriction lever operatively connected to said pawl, a transfer leverpivotally connected to said operating rod, means rotatably connectingsaid friction lever and said transfer lever to said control bracket,yieldable means between the friction lever and said pawl for allowingvertical displacement of the operating rod without disturbing the pawlwhen the latter is in locked engagement with the catch, and meansproviding a lost motion connection between said transfer lever and saidfriction lever, the parts ,being constructed and arranged so that uponrocking of the foot member relative to the calf member in one direction,when the thigh member and calf member arein alignment, for moving, thepawl into locking engagement with said catch and when said foot memberis moved in an opposite direction relative, to the calf member forreleasing the engagement of the pawl with said catch.

8. In an artificial limb, a thigh member having a locking catch in thebottom thereof, a calf member, pivot means extending transversely of thethigh member for connecting the upper end of the calf member thereto toprovide a movable knee joint, a bar rotatably connected to said pivotmeans and extending downwardly into said calf member, means connectingsaid bar to said calf member, a foot member pivotally connected to thelower end of said calf member, a locking pawl pivotally connected tosaid bar and arranged to be moved into and out of locking engagementwith said catch, a control bracket connected to said bar and having aninwardly extending arm provided with an opening, a friction lever on oneside of said control bracket, a transfer lever on the opposite side ofsaid bracket, a spring washer adjacent said friction lever, a frictionwasher adjacent said transfer lever, said levers and said washers havingaligned transverse openings, a clamping bolt extending through, saidopenings for rotatably connecting said levers and said washers to saidcontrol bracket, an operating rod pivotally connectedat its upper end tosaid transfer lever, means operatively connecting said friction lever tosaid pawl, means providing a lost motion connection between saidtransverse lever and said friction lever, means providing a lost motionconnection between said friction lever and said pawl, and meansoperatively connecting the lower end of said rod to said foot member,the parts being constructed and arranged so that upon rocking of thefoot member relative to the calf member in one direction when the thighmember and calf member are in alignment for moving the pawl into lockingengagement with said catch, and when said foot member-is moved in anopposite direction relative to the calf member for releasing theengagement of the pawl with said catch. 7

9. A knee lock for artificial limbs including a fixed bracket connectedto a limb member, a support rotatably connected to said bracket, afriction lever carried by said support, a transfer lever carried by thesupport, a pawl pivotally connected to the lock, means operativelyconnecting the friction lever to said pawl, and an operating memberconnected to said transfer lever for operating the pawl upon rotation ofsaid levers by the operating member.

10. A knee lock for artificial limbs including a fixed bracket connectedto a limb member, a support rotatably connected to said bracket, afriction lever carried by said support, a transfer lever carried by thesupport, a pawl pivotally connected to the lock, means operativelyconnecting the friction lever to said pawl, an operating memberconnected to said transfer lever for operating the pawl upon rotation ofsaid levers by the operating member, and means providing a lost motionconnection between the transfer lever and the friction lever.

11. A knee lock for artificial limbs including a fixed bracket connectedto a limb member, a support rotatably connected to said bracket, afriction lever carried by said support, a transfer lever carried by thesupport, a pawl pivotally connected to the lock above said bracket,means operatively connecting the friction lever to said pawl, anoperating member connected to said transfer lever for moving the pawlupon rotation of said levers by the operating member, and means forproviding a lost motion connection between the friction lever and saidpawl.

12. A knee lock for artificial limbs including a fixed bracket connectedto a limb member, a pin rotatably connected to said bracket, a frictionlever carried by said pin on one side of said bracket, a transfer levercarried by said pin on the opposite side of said bracket, a locking pawlpivoted to said lock above said bracket, a rod connected to. said pawland extending loosely through said friction lever, a coil springsurrounding said rod and confined between said friction lever and saidpawl for providing a lost motion connection between the friction leverand the pawl, and an operating member pivotally connected to thetransfer lever for rotating the transfer lever and the friction lever soas to operate said pawl.

13. A knee lock for artificial limbs including a fixed bracket connectedto a limb member, a pin rotatably connected to said bracket, a, frictionlever carried by said pin on one side of said bracket, a transfer levercarried by said pin on the opposite side of said bracket, 9, lockingpawl pivoted to the knee lock above said bracket, a rod connected tosaid pawl and extending loosely through said friction lever, a coilspring surrounding said rod and confined between said friction lever andsaid pawl for providing a lost motion connection between the frictionlever and the pawl, means providing a lost motion connection between thetransfer lever and the friction lever, and an operating member pivotallyconnected to the transfer lever for rotating the transfer lever and thefriction lever so as to operate said pawl.

14. An artificial limb having in combination, a thigh member providedwith a catch, a calf member pivotally connected to said thigh member, afoot member pivotally connected to said calf member, a knee lockmechanism connected to the calf member and including a pawl arranged tobe moved into and out of engagement with said catch, a control bracketconnected to the calf member, a friction member rotatably connected tosaid bracket, means operatively connecting said friction member to saidpawl, a transfer member rotatably connected to said bracket, meansoperatively connecting said transfer member to said friction member, anoperating rod connected at its lower end to said foot member, and meansconnecting the upper end of said rod to said transfer member, the partsbeing constructed and arranged so that upon rocking movement of the footmember in one direction to cause the operating rod to actuate thetransfer member and the friction member to move the pawl into engagementwith the catch and upon movement of the foot :member in an oppositedirection to actuate the operating rod, the transfer member and thefriction lever so as to disengage the pawl from the catch. 15. Anartificial limb as called for in claim 14 in which the transfer memberand the friction member have coacting means for providing a lost motionconnection between said members.

JAMES E. HANGER, III.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 9,202 Russell Aug. 17, 18522,071,711 Sprouls Feb. 23, 1937 FOREIGN PATENTS Number Country Date171,613 Great Britain Nov. 24, 1921 518,258 Great Britain Feb. 21, 1940

